1. Field of the Invention
This invention relates generally to adhesive labels, and more particularly to a system and method for forming discrete etched adhesive labels from continuous label stock.
2. Description of the Background Art
Vendors of consumer products commonly affix adhesive labels to the product for the purposes of identification and aesthetics. To generate enhanced consumer appeal, the vendor may use adhesive labels having an unusual and/or visually attractive design. One particularly effective method of producing attractive labels is to provide them with an intricate geometry, which may comprise one or more etched regions formed in the label.
Adhesive labels are typically manufactured from rolls or strips of continuous label stock. The label stock comprises a face stock having a front surface and an adhesive-coated rear surface. Underlying the face stock is a release liner. The release liner is provided with a low-adhesion surface contacting the face stock such that the release liner may be easily separated from the face stock just prior to the application of the adhesive labels to the labeled products. The inclusion of the release liner prevents contamination of the adhesive surface, allows the label stock to be handled without undesirable adherence to adjacent surfaces, and provides structural integrity.
Various techniques may be employed to produce etched regions in label stock. While mechanical methods are available for this purpose, laser-based methods offer substantial benefits in terms of precision and versatility. U.S. Pat. No. 4,430,548, issued to John Macken, discloses an exemplary laser-based technique wherein a laser beam having sufficient power density is directed by a template and optical components onto a workpiece such that a predetermined area or areas of the workpiece is or are vaporized, thereby producing the desired pattern of etched regions.
One disadvantage associated with the use of the foregoing laser-based technique to produce etched labels is that the laser beam will typically vaporize not only the face stock, but also a portion of the release liner underlying the etched region of the face stock. Damage to the release liner can compromise the structural integrity of the label stock and thereby lead to tearing or breakage. When tearing or breakage occurs during processing of the label stock, the operation of the label-processing equipment must be stopped while the damaged label stock is removed and discarded and new label stock is threaded through the equipment. Multiple shutdowns necessitated by tearing or breakage of label stock reduces the overall availability of the processing equipment and may significantly raise the costs associated with its operation. Furthermore, damage to the release liner may render separation of the release liner from the face stock difficult, thus greatly complicating the task of applying the labels to the products.
Damage to the release liner may be reduced by precisely setting the laser beam power density and scanning speed such that only the face stock is vaporized, leaving the release liner substantially intact. However, this method is difficult to implement and may be thwarted by any nonuniformities in the properties of the face stock, such as variations of thickness or composition.
In view of the foregoing discussion, there is a need for a system and method for producing etched adhesive labels from continuous label stock wherein the release liner is not damaged by the action of the laser utilized to create etched regions.